Publications
2023 |
Cahyanto, Arief; Martins, Marcos Vinicius Surmani; Bianchi, Otavio; Sudhakaran, Deepa Perumbodathu; Sililkas, Nikolaos; Echeverrigaray, Sergio Graniero; Rosa, Vinicius Graphene oxide increases PMMA's resistance to fatigue and strength degradation Journal Article DENTAL MATERIALS, 39 (9), pp. 763-769, 2023, ISSN: 0109-5641. @article{ISI:001065166400001, title = {Graphene oxide increases PMMA's resistance to fatigue and strength degradation}, author = {Arief Cahyanto and Marcos Vinicius Surmani Martins and Otavio Bianchi and Deepa Perumbodathu Sudhakaran and Nikolaos Sililkas and Sergio Graniero Echeverrigaray and Vinicius Rosa}, doi = {10.1016/j.dental.2023.06.009}, times_cited = {0}, issn = {0109-5641}, year = {2023}, date = {2023-08-23}, journal = {DENTAL MATERIALS}, volume = {39}, number = {9}, pages = {763-769}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {Objectives: to characterize the effects of graphene oxide (GO) on polymethyl methacrylate's (PMMA) reliability and lifetime. The hypothesis tested was that GO would increase both Weibull parameters and decreased strength degradation over time. Methods: PMMA disks containing GO (0.01, 0.05, 0.1, or 0.5 wt%) were subjected to a biaxial flexural test to determine the Weibull parameters (m: modulus of Weibull; & sigma;0: characteristic strength; n = 30 at 1 MPa/s) and slow crack growth (SCG) parameters (n: subcritical crack growth susceptibility coefficient, & sigma;f0: scaling parameter; n = 10 at 10-2, 10-1, 101, 100 and 102 MPa/s). Strength-probability-time (SPT) diagrams were plotted by merging SCG and Weibull parameters. Results: There was no significant difference in the m value of all materials. However, 0.5 GO presented the lowest & sigma;0, whereas all other groups were similar. The lowest n value obtained for all GO-modified PMMA groups (27.4 for 0.05 GO) was higher than the Control (15.6). The strength degradation predicted after 15 years for Control was 12%, followed by 0.01 GO (7%), 0.05 GO (9%), 0.1 GO (5%), and 0.5 GO (1%). Significance: The hypothesis was partially accepted as GO increased PMMA's fatigue resistance and lifetime but did not significantly improve its Weibull parameters. GO added to PMMA did not significantly affect the initial strength and reliability but significantly increased PMMA's predicted lifetime. All the GO-containing groups presented higher resistance to fracture at all times analyzed compared with the Control, with the best overall results observed for 0.1 GO.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Objectives: to characterize the effects of graphene oxide (GO) on polymethyl methacrylate's (PMMA) reliability and lifetime. The hypothesis tested was that GO would increase both Weibull parameters and decreased strength degradation over time. Methods: PMMA disks containing GO (0.01, 0.05, 0.1, or 0.5 wt%) were subjected to a biaxial flexural test to determine the Weibull parameters (m: modulus of Weibull; & sigma;0: characteristic strength; n = 30 at 1 MPa/s) and slow crack growth (SCG) parameters (n: subcritical crack growth susceptibility coefficient, & sigma;f0: scaling parameter; n = 10 at 10-2, 10-1, 101, 100 and 102 MPa/s). Strength-probability-time (SPT) diagrams were plotted by merging SCG and Weibull parameters. Results: There was no significant difference in the m value of all materials. However, 0.5 GO presented the lowest & sigma;0, whereas all other groups were similar. The lowest n value obtained for all GO-modified PMMA groups (27.4 for 0.05 GO) was higher than the Control (15.6). The strength degradation predicted after 15 years for Control was 12%, followed by 0.01 GO (7%), 0.05 GO (9%), 0.1 GO (5%), and 0.5 GO (1%). Significance: The hypothesis was partially accepted as GO increased PMMA's fatigue resistance and lifetime but did not significantly improve its Weibull parameters. GO added to PMMA did not significantly affect the initial strength and reliability but significantly increased PMMA's predicted lifetime. All the GO-containing groups presented higher resistance to fracture at all times analyzed compared with the Control, with the best overall results observed for 0.1 GO. |
Yang, Kou; Hu, Zhitao; Li, Xiaolai; Nikolaev, Konstantin; Hong, Gan Kai; Mamchik, Natalia; Erofeev, Ivan; Mirsaidov, Utkur M; Neto, Antonio Castro H; Blackwood, Daniel J; Shchukin, Dmitry G; Trushin, Maxim; Novoselov, Kostya S; Andreeva, Daria V Graphene oxide-polyamine preprogrammable nanoreactors with sensing capability for corrosion protection of materials Journal Article PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 120 (35), 2023, ISSN: 0027-8424. @article{ISI:001112759000007, title = {Graphene oxide-polyamine preprogrammable nanoreactors with sensing capability for corrosion protection of materials}, author = {Kou Yang and Zhitao Hu and Xiaolai Li and Konstantin Nikolaev and Gan Kai Hong and Natalia Mamchik and Ivan Erofeev and Utkur M Mirsaidov and Antonio Castro H Neto and Daniel J Blackwood and Dmitry G Shchukin and Maxim Trushin and Kostya S Novoselov and Daria V Andreeva}, doi = {10.1073/pnas.2307618120}, times_cited = {0}, issn = {0027-8424}, year = {2023}, date = {2023-08-21}, journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, volume = {120}, number = {35}, publisher = {NATL ACAD SCIENCES}, address = {2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA}, abstract = {Corrosion is one of the major issues for sustainable manufacturing globally. The annual global cost of corrosion is US$2.5 trillion (approximately 3.4% of the world's GDP). The traditional ways of corrosion protection (such as barriers or inhibiting) are either not very effective (in the case of barrier protection) or excessively expensive (inhibiting). Here, we demonstrate a concept of nanoreactors, which are able to controllably release or adsorb protons or hydroxides directly on corrosion sites, hence, selectively regulating the corrosion reactions. A single nanoreactor comprises a nano compartment wrapped around by a pH-sensing membrane represented, respectively, by a halloysite nanotube and a graphene oxide/polyamine envelope. A nanoreactor response is determined by the change of a signaling pH on a given corrosion site. The nanoreactors are self-assembled and suitable for mass line production. The concept creates sustainable technology for developing smart anticorrosion coatings, which are nontoxic, selective, and inexpensive.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Corrosion is one of the major issues for sustainable manufacturing globally. The annual global cost of corrosion is US$2.5 trillion (approximately 3.4% of the world's GDP). The traditional ways of corrosion protection (such as barriers or inhibiting) are either not very effective (in the case of barrier protection) or excessively expensive (inhibiting). Here, we demonstrate a concept of nanoreactors, which are able to controllably release or adsorb protons or hydroxides directly on corrosion sites, hence, selectively regulating the corrosion reactions. A single nanoreactor comprises a nano compartment wrapped around by a pH-sensing membrane represented, respectively, by a halloysite nanotube and a graphene oxide/polyamine envelope. A nanoreactor response is determined by the change of a signaling pH on a given corrosion site. The nanoreactors are self-assembled and suitable for mass line production. The concept creates sustainable technology for developing smart anticorrosion coatings, which are nontoxic, selective, and inexpensive. |
Vu, Nam Thanh Trung; Loh, Leyi; Chen, Yuan; Wu, Qingyun; Verzhbitskiy, Ivan A A; Watanabe, Kenji; Taniguchi, Takashi; Bosman, Michel; Ang, Yee Sin; Ang, Lay Kee; Trushin, Maxim; Eda, Goki Single Atomic Defect Conductivity for Selective Dilute Impurity Imaging in 2D Semiconductors Journal Article ACS NANO, 17 (16), pp. 15648-15655, 2023, ISSN: 1936-0851. @article{ISI:001048113400001, title = {Single Atomic Defect Conductivity for Selective Dilute Impurity Imaging in 2D Semiconductors}, author = {Nam Thanh Trung Vu and Leyi Loh and Yuan Chen and Qingyun Wu and Ivan A A Verzhbitskiy and Kenji Watanabe and Takashi Taniguchi and Michel Bosman and Yee Sin Ang and Lay Kee Ang and Maxim Trushin and Goki Eda}, doi = {10.1021/acsnano.3c02758}, times_cited = {0}, issn = {1936-0851}, year = {2023}, date = {2023-08-11}, journal = {ACS NANO}, volume = {17}, number = {16}, pages = {15648-15655}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Precisely controlled impurity doping is of fundamentalsignificancein modern semiconductor technologies. Desired physical propertiesare often achieved at impurity concentrations well below parts permillion level. For emergent two-dimensional semiconductors, developmentof reliable doping strategies is hindered by the inherent difficultyin identifying and quantifying impurities in such a dilute limit wherethe absolute number of atoms to be detected is insufficient for commonanalytical techniques. Here we report rapid high-contrast imagingof dilute single atomic impurities by using conductive atomic forcemicroscopy. We show that the local conductivity is enhanced by morethan 100-fold by a single impurity atom due to resonance-assistedtunneling. Unlike the closely related scanning tunneling microscopy,the local conductivity sensitively depends on the impurity energylevel, allowing minority defects to be selectively imaged. We furtherdemonstrate subsurface impurity detection with single monolayer depthresolution in multilayer materials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Precisely controlled impurity doping is of fundamentalsignificancein modern semiconductor technologies. Desired physical propertiesare often achieved at impurity concentrations well below parts permillion level. For emergent two-dimensional semiconductors, developmentof reliable doping strategies is hindered by the inherent difficultyin identifying and quantifying impurities in such a dilute limit wherethe absolute number of atoms to be detected is insufficient for commonanalytical techniques. Here we report rapid high-contrast imagingof dilute single atomic impurities by using conductive atomic forcemicroscopy. We show that the local conductivity is enhanced by morethan 100-fold by a single impurity atom due to resonance-assistedtunneling. Unlike the closely related scanning tunneling microscopy,the local conductivity sensitively depends on the impurity energylevel, allowing minority defects to be selectively imaged. We furtherdemonstrate subsurface impurity detection with single monolayer depthresolution in multilayer materials. |
Kurumi, Satoshi; Sugawa, Kosuke; Takase, Kouichi; Darma, Yudi; Sagara, Takuya; Matsuda, Ken-ichi; Suzuki, Kaoru; Ong, Bin Leong; Rusydi, Andrivo APPLIED PHYSICS LETTERS, 123 (5), 2023, ISSN: 0003-6951. @article{ISI:001042281800009, title = {Growth of highly oriented crystalline gold nanoislands on MgO(001) substrates for surface-enhanced Raman scattering chips by pulsed laser deposition}, author = {Satoshi Kurumi and Kosuke Sugawa and Kouichi Takase and Yudi Darma and Takuya Sagara and Ken-ichi Matsuda and Kaoru Suzuki and Bin Leong Ong and Andrivo Rusydi}, doi = {10.1063/5.0152610}, times_cited = {0}, issn = {0003-6951}, year = {2023}, date = {2023-07-31}, journal = {APPLIED PHYSICS LETTERS}, volume = {123}, number = {5}, publisher = {AIP Publishing}, address = {1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA}, abstract = {Highly oriented crystalline gold nanoislands (NIs) are self-assembled on MgO(001) substrates by pulsed laser deposition. Morphologies of the gold NIs are significantly dependent on the substrate temperature during gold deposition. Symmetrical-shaped NIs with Au(111) orientation are existence parallel to the MgO(001) substrate at low temperatures deposition (350 and 550 ?), while square-shaped and hexagonal-shaped gold NIs are co-existence whose crystallinity was Au(001) and Au(111), respectively. Extinction spectra of the gold NIs on MgO(001) substrates show that wide-range of photo-energy is disappeared. For a simple and useful plasmonic device, the produced gold NIs on MgO(001) substrates are applied to the surface-enhanced Raman scattering (SERS) chips. The SERS properties of the chips are evaluated using 4-MBA as a model analyte. From the SERS signal of a 4-MBA ring breathing mode, we obtain a significant enhancement factor over 10(7), which is approximately 10 times higher than that of a conventional SERS chip.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Highly oriented crystalline gold nanoislands (NIs) are self-assembled on MgO(001) substrates by pulsed laser deposition. Morphologies of the gold NIs are significantly dependent on the substrate temperature during gold deposition. Symmetrical-shaped NIs with Au(111) orientation are existence parallel to the MgO(001) substrate at low temperatures deposition (350 and 550 ?), while square-shaped and hexagonal-shaped gold NIs are co-existence whose crystallinity was Au(001) and Au(111), respectively. Extinction spectra of the gold NIs on MgO(001) substrates show that wide-range of photo-energy is disappeared. For a simple and useful plasmonic device, the produced gold NIs on MgO(001) substrates are applied to the surface-enhanced Raman scattering (SERS) chips. The SERS properties of the chips are evaluated using 4-MBA as a model analyte. From the SERS signal of a 4-MBA ring breathing mode, we obtain a significant enhancement factor over 10(7), which is approximately 10 times higher than that of a conventional SERS chip. |
Fu, Bing; Mao, Xianwen; Park, Youngchan; Zhao, Zhiheng; Yan, Tianlei; Jung, Won; Francis, Danielle H; Li, Wenjie; Pian, Brooke; Salimijazi, Farshid; Suri, Mokshin; Hanrath, Tobias; Barstow, Buz; Chen, Peng Single-cell multimodal imaging uncovers energy conversion pathways in biohybrids Journal Article NATURE CHEMISTRY, 15 (10), pp. 1400-+, 2023, ISSN: 1755-4330. @article{ISI:001038592700001, title = {Single-cell multimodal imaging uncovers energy conversion pathways in biohybrids}, author = {Bing Fu and Xianwen Mao and Youngchan Park and Zhiheng Zhao and Tianlei Yan and Won Jung and Danielle H Francis and Wenjie Li and Brooke Pian and Farshid Salimijazi and Mokshin Suri and Tobias Hanrath and Buz Barstow and Peng Chen}, doi = {10.1038/s41557-023-01285-z}, times_cited = {0}, issn = {1755-4330}, year = {2023}, date = {2023-07-27}, journal = {NATURE CHEMISTRY}, volume = {15}, number = {10}, pages = {1400-+}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Microbe-semiconductor biohybrids, which integrate microbial enzymatic synthesis with the light-harvesting capabilities of inorganic semiconductors, have emerged as promising solar-to-chemical conversion systems. Improving the electron transport at the nano-bio interface and inside cells is important for boosting conversion efficiencies, yet the underlying mechanism is challenging to study by bulk measurements owing to the heterogeneities of both constituents. Here we develop a generalizable, quantitative multimodal microscopy platform that combines multi-channel optical imaging and photocurrent mapping to probe such biohybrids down to single- to sub-cell/particle levels. We uncover and differentiate the critical roles of different hydrogenases in the lithoautotrophic bacterium Ralstonia eutropha for bioplastic formation, discover this bacterium's surprisingly large nanoampere-level electron-uptake capability, and dissect the cross-membrane electron-transport pathways. This imaging platform, and the associated analytical framework, can uncover electron-transport mechanisms in various types of biohybrid, and potentially offers a means to use and engineer R. eutropha for efficient chemical production coupled with photocatalytic materials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Microbe-semiconductor biohybrids, which integrate microbial enzymatic synthesis with the light-harvesting capabilities of inorganic semiconductors, have emerged as promising solar-to-chemical conversion systems. Improving the electron transport at the nano-bio interface and inside cells is important for boosting conversion efficiencies, yet the underlying mechanism is challenging to study by bulk measurements owing to the heterogeneities of both constituents. Here we develop a generalizable, quantitative multimodal microscopy platform that combines multi-channel optical imaging and photocurrent mapping to probe such biohybrids down to single- to sub-cell/particle levels. We uncover and differentiate the critical roles of different hydrogenases in the lithoautotrophic bacterium Ralstonia eutropha for bioplastic formation, discover this bacterium's surprisingly large nanoampere-level electron-uptake capability, and dissect the cross-membrane electron-transport pathways. This imaging platform, and the associated analytical framework, can uncover electron-transport mechanisms in various types of biohybrid, and potentially offers a means to use and engineer R. eutropha for efficient chemical production coupled with photocatalytic materials. |
Zhang, Qi; Hossain, Md. Shafayat; Casas, Brian; Zheng, Wenkai; Cheng, Zi-Jia; Lai, Zhuangchai; Tu, Yi-Hsin; Chang, Guoqing; Yao, Yao; Li, Siyuan; Jiang, Yu-Xiao; Mardanya, Sougata; Chang, Tay-Rong; You, Jing-Yang; Feng, Yuan-Ping; Cheng, Guangming; Yin, Jia-Xin; Shumiya, Nana; Cochran, Tyler A; Yang, Xian P; Litskevich, Maksim; Yao, Nan; Watanabe, Kenji; Taniguchi, Takashi; Zhang, Hua; Balicas, Luis; Hasan, Zahid M Ultrahigh supercurrent density in a two-dimensional topological material Journal Article PHYSICAL REVIEW MATERIALS, 7 (7), 2023, ISSN: 2475-9953. @article{ISI:001051438100007, title = {Ultrahigh supercurrent density in a two-dimensional topological material}, author = {Qi Zhang and Md. Shafayat Hossain and Brian Casas and Wenkai Zheng and Zi-Jia Cheng and Zhuangchai Lai and Yi-Hsin Tu and Guoqing Chang and Yao Yao and Siyuan Li and Yu-Xiao Jiang and Sougata Mardanya and Tay-Rong Chang and Jing-Yang You and Yuan-Ping Feng and Guangming Cheng and Jia-Xin Yin and Nana Shumiya and Tyler A Cochran and Xian P Yang and Maksim Litskevich and Nan Yao and Kenji Watanabe and Takashi Taniguchi and Hua Zhang and Luis Balicas and Zahid M Hasan}, doi = {10.1103/PhysRevMaterials.7.L071801}, times_cited = {0}, issn = {2475-9953}, year = {2023}, date = {2023-07-26}, journal = {PHYSICAL REVIEW MATERIALS}, volume = {7}, number = {7}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {Ongoing advances in superconductors continue to revolutionize technology thanks to the increasingly versatile and robust availability of lossless supercurrents. In particular, high supercurrent density can lead to more efficient and compact power transmission lines, high-field magnets, as well as high-performance nanoscale radiation detectors and superconducting spintronics. Here, we report the discovery of an unprecedentedly high superconducting critical current density (17 MA/cm(2) at 0 T and 7 MA/cm(2) at 8 T) in 1T'-WS2, exceeding those of all reported two-dimensional superconductors to date. 1T'-WS2 features a strongly anisotropic (both in- and out-ofplane) superconducting state that violates the Pauli paramagnetic limit signaling the presence of unconventional superconductivity. Spectroscopic imaging of the vortices further substantiates the anisotropic nature of the superconducting state. More intriguingly, the normal state of 1T'-WS2 carries topological properties. The band structure obtained via angle-resolved photoemission spectroscopy and first-principles calculations points to a Z(2) topological invariant. The concomitance of topology and superconductivity in 1T'-WS2 establishes it as a topological superconductor candidate, which is promising for the development of quantum computing technology.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Ongoing advances in superconductors continue to revolutionize technology thanks to the increasingly versatile and robust availability of lossless supercurrents. In particular, high supercurrent density can lead to more efficient and compact power transmission lines, high-field magnets, as well as high-performance nanoscale radiation detectors and superconducting spintronics. Here, we report the discovery of an unprecedentedly high superconducting critical current density (17 MA/cm(2) at 0 T and 7 MA/cm(2) at 8 T) in 1T'-WS2, exceeding those of all reported two-dimensional superconductors to date. 1T'-WS2 features a strongly anisotropic (both in- and out-ofplane) superconducting state that violates the Pauli paramagnetic limit signaling the presence of unconventional superconductivity. Spectroscopic imaging of the vortices further substantiates the anisotropic nature of the superconducting state. More intriguingly, the normal state of 1T'-WS2 carries topological properties. The band structure obtained via angle-resolved photoemission spectroscopy and first-principles calculations points to a Z(2) topological invariant. The concomitance of topology and superconductivity in 1T'-WS2 establishes it as a topological superconductor candidate, which is promising for the development of quantum computing technology. |
Foo, D C W; Swain, N; Sengupta, P; Lemarie, G; Adam, S Stabilization mechanism for many-body localization in two dimensions Journal Article PHYSICAL REVIEW RESEARCH , 5 (3), 2023. @article{ISI:001050777700001, title = {Stabilization mechanism for many-body localization in two dimensions }, author = {D C W Foo and N Swain and P Sengupta and G Lemarie and S Adam}, doi = {10.1103/PhysRevResearch.5.L032011}, times_cited = {0}, year = {2023}, date = {2023-07-20}, journal = {PHYSICAL REVIEW RESEARCH }, volume = {5}, number = {3}, publisher = {AMER PHYSICAL SOC }, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA }, abstract = {Experiments in cold-atom systems see almost identical signatures of many-body localization (MBL) in both one-dimensional (d = 1) and two-dimensional (d = 2) systems despite the thermal avalanche hypothesis showing that the MBL phase is unstable ford > 1. Underpinning the thermal avalanche argument is the assumption of exponential localization of local integrals of motion (LIOM). In this Letter we demonstrate that the addition of a confining potential-as is typical in experimental setups-allows a noninteracting disordered system to have superexponentially (Gaussian) localized wave functions, and an interacting disordered system to undergo a localization transition. Moreover, we show that Gaussian localization of MBL LIOM shifts the quantum avalanche critical dimension from d = 1 to d = 2, potentially bridging the divide between the experimental demonstrations of MBL in these systems and existing theoretical arguments that claim that such demonstrations are impossible. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Experiments in cold-atom systems see almost identical signatures of many-body localization (MBL) in both one-dimensional (d = 1) and two-dimensional (d = 2) systems despite the thermal avalanche hypothesis showing that the MBL phase is unstable ford > 1. Underpinning the thermal avalanche argument is the assumption of exponential localization of local integrals of motion (LIOM). In this Letter we demonstrate that the addition of a confining potential-as is typical in experimental setups-allows a noninteracting disordered system to have superexponentially (Gaussian) localized wave functions, and an interacting disordered system to undergo a localization transition. Moreover, we show that Gaussian localization of MBL LIOM shifts the quantum avalanche critical dimension from d = 1 to d = 2, potentially bridging the divide between the experimental demonstrations of MBL in these systems and existing theoretical arguments that claim that such demonstrations are impossible. |
Wang, Zishen; You, Jing-Yang; Chen, Chuan; Mo, Jinchao; He, Jingyu; Zhang, Lishu; Zhou, Jun; Loh, Kian Ping; Feng, Yuan Ping Interplay of the charge density wave transition with topological and superconducting properties Journal Article NANOSCALE HORIZONS, 8 (10), pp. 1395-1402, 2023, ISSN: 2055-6756. @article{ISI:001033202800001, title = {Interplay of the charge density wave transition with topological and superconducting properties}, author = {Zishen Wang and Jing-Yang You and Chuan Chen and Jinchao Mo and Jingyu He and Lishu Zhang and Jun Zhou and Kian Ping Loh and Yuan Ping Feng}, doi = {10.1039/d3nh00207a}, times_cited = {0}, issn = {2055-6756}, year = {2023}, date = {2023-07-18}, journal = {NANOSCALE HORIZONS}, volume = {8}, number = {10}, pages = {1395-1402}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {Exotic phenomena due to the interplay of different quantum orders have been observed and the study of these phenomena has emerged as a new frontier in condensed matter research, especially in the two-dimensional limit. Here, we report the coexistence of charge density waves (CDWs), superconductivity, and nontrivial topology in monolayer 1H-MSe2 (M = Nb, Ta) triggered by momentum-dependent electron-phonon coupling through electron doping. At a critical electron doping concentration, new 2 x 2 CDW phases emerge with nontrivial topology, Dirac cones, and van Hove singularities. Interestingly, these 2 x 2 CDW phases are also superconducting. Our findings not only reveal a route towards realizing nontrivial electronic characters by CDW engineering, but also provide an exciting platform to modulate different quantum states at the confluence of CDWs, superconductivity, nontrivial topology, and electron-phonon coupling.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Exotic phenomena due to the interplay of different quantum orders have been observed and the study of these phenomena has emerged as a new frontier in condensed matter research, especially in the two-dimensional limit. Here, we report the coexistence of charge density waves (CDWs), superconductivity, and nontrivial topology in monolayer 1H-MSe2 (M = Nb, Ta) triggered by momentum-dependent electron-phonon coupling through electron doping. At a critical electron doping concentration, new 2 x 2 CDW phases emerge with nontrivial topology, Dirac cones, and van Hove singularities. Interestingly, these 2 x 2 CDW phases are also superconducting. Our findings not only reveal a route towards realizing nontrivial electronic characters by CDW engineering, but also provide an exciting platform to modulate different quantum states at the confluence of CDWs, superconductivity, nontrivial topology, and electron-phonon coupling. |
Hu, Junxiong; Tan, Junyou; Ezzi, Mohammed Al M; Chattopadhyay, Udvas; Gou, Jian; Zheng, Yuntian; Wang, Zihao; Chen, Jiayu; Thottathil, Reshmi; Luo, Jiangbo; Watanabe, Kenji; Taniguchi, Takashi; Wee, Andrew Thye Shen; Adam, Shaffique; Ariando, A Controlled alignment of supermoire lattice in double-aligned graphene heterostructures Journal Article NATURE COMMUNICATIONS, 14 (1), 2023. @article{ISI:001029450400007, title = {Controlled alignment of supermoire lattice in double-aligned graphene heterostructures}, author = {Junxiong Hu and Junyou Tan and Mohammed Al M Ezzi and Udvas Chattopadhyay and Jian Gou and Yuntian Zheng and Zihao Wang and Jiayu Chen and Reshmi Thottathil and Jiangbo Luo and Kenji Watanabe and Takashi Taniguchi and Andrew Thye Shen Wee and Shaffique Adam and A Ariando}, doi = {10.1038/s41467-023-39893-5}, times_cited = {0}, year = {2023}, date = {2023-07-12}, journal = {NATURE COMMUNICATIONS}, volume = {14}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {The supermoire lattice, built by stacking two moire patterns, provides a platform for creating flat mini-bands and studying electron correlations. An ultimate challenge in assembling a graphene supermoire lattice is in the deterministic control of its rotational alignment, which is made highly aleatory due to the random nature of the edge chirality and crystal symmetry. Employing the so-called "golden rule of three", here we present an experimental strategy to overcome this challenge and realize the controlled alignment of double-aligned hBN/graphene/hBN supermoire lattice, where the twist angles between graphene and top/bottom hBN are both close to zero. Remarkably, we find that the crystallographic edge of neighboring graphite can be used to better guide the stacking alignment, as demonstrated by the controlled production of 20 moire samples with an accuracy better than similar to 0.2 degrees. Finally, we extend our technique to low-angle twisted bilayer graphene and ABC-stacked trilayer graphene, providing a strategy for flat-band engineering in these moirematerials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The supermoire lattice, built by stacking two moire patterns, provides a platform for creating flat mini-bands and studying electron correlations. An ultimate challenge in assembling a graphene supermoire lattice is in the deterministic control of its rotational alignment, which is made highly aleatory due to the random nature of the edge chirality and crystal symmetry. Employing the so-called "golden rule of three", here we present an experimental strategy to overcome this challenge and realize the controlled alignment of double-aligned hBN/graphene/hBN supermoire lattice, where the twist angles between graphene and top/bottom hBN are both close to zero. Remarkably, we find that the crystallographic edge of neighboring graphite can be used to better guide the stacking alignment, as demonstrated by the controlled production of 20 moire samples with an accuracy better than similar to 0.2 degrees. Finally, we extend our technique to low-angle twisted bilayer graphene and ABC-stacked trilayer graphene, providing a strategy for flat-band engineering in these moirematerials. |
Zhu, Yiru; Lim, Juhwan; Zhang, Zhepeng; Wang, Yan; Sarkar, Soumya; Ramsden, Hugh; Li, Yang; Yan, Han; Phuyal, Dibya; Gauriot, Nicolas; Rao, Akshay; Hoye, Robert L Z; Eda, Goki; Chhowalla, Manish Room-Temperature Photoluminescence Mediated by Sulfur Vacancies in 2D Molybdenum Disulfide Journal Article ACS NANO, 17 (14), pp. 13545-13553, 2023, ISSN: 1936-0851. @article{ISI:001024802200001, title = {Room-Temperature Photoluminescence Mediated by Sulfur Vacancies in 2D Molybdenum Disulfide}, author = {Yiru Zhu and Juhwan Lim and Zhepeng Zhang and Yan Wang and Soumya Sarkar and Hugh Ramsden and Yang Li and Han Yan and Dibya Phuyal and Nicolas Gauriot and Akshay Rao and Robert L Z Hoye and Goki Eda and Manish Chhowalla}, doi = {10.1021/acsnano.3c02103}, times_cited = {0}, issn = {1936-0851}, year = {2023}, date = {2023-07-07}, journal = {ACS NANO}, volume = {17}, number = {14}, pages = {13545-13553}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Atomic defects inmonolayer transition metal dichalcogenides (TMDs)such as chalcogen vacancies significantly affect their properties.In this work, we provide a reproducible and facile strategy to rationallyinduce chalcogen vacancies in monolayer MoS2 by annealingat 600 & DEG;C in an argon/hydrogen (95%/5%) atmosphere. SynchrotronX-ray photoelectron spectroscopy shows that a Mo 3d(5/2) corepeak at 230.1 eV emerges in the annealed MoS2 associatedwith nonstoichiometric MoS x (0 < x < 2), and Raman spectroscopy shows an enhancement ofthe & SIM;380 cm(-1) peak that is attributed tosulfur vacancies. At sulfur vacancy densities of & SIM;1.8 x10(14) cm(-2), we observe a defect peak at & SIM;1.72 eV (referred to as LXD) at room temperaturein the photoluminescence (PL) spectrum. The LXD peak isattributed to excitons trapped at defect-induced in-gap states andis typically observed only at low temperatures (& LE;77 K). Time-resolvedPL measurements reveal that the lifetime of defect-mediated LXD emission is longer than that of band edge excitons, bothat room and low temperatures (& SIM;2.44 ns at 8 K). The LXD peak can be suppressed by annealing the defective MoS2 in sulfur vapor, which indicates that it is possible to passivatethe vacancies. Our results provide insights into how excitonic anddefect-mediated PL emissions in MoS2 are influenced bysulfur vacancies at room and low temperatures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Atomic defects inmonolayer transition metal dichalcogenides (TMDs)such as chalcogen vacancies significantly affect their properties.In this work, we provide a reproducible and facile strategy to rationallyinduce chalcogen vacancies in monolayer MoS2 by annealingat 600 & DEG;C in an argon/hydrogen (95%/5%) atmosphere. SynchrotronX-ray photoelectron spectroscopy shows that a Mo 3d(5/2) corepeak at 230.1 eV emerges in the annealed MoS2 associatedwith nonstoichiometric MoS x (0 < x < 2), and Raman spectroscopy shows an enhancement ofthe & SIM;380 cm(-1) peak that is attributed tosulfur vacancies. At sulfur vacancy densities of & SIM;1.8 x10(14) cm(-2), we observe a defect peak at & SIM;1.72 eV (referred to as LXD) at room temperaturein the photoluminescence (PL) spectrum. The LXD peak isattributed to excitons trapped at defect-induced in-gap states andis typically observed only at low temperatures (& LE;77 K). Time-resolvedPL measurements reveal that the lifetime of defect-mediated LXD emission is longer than that of band edge excitons, bothat room and low temperatures (& SIM;2.44 ns at 8 K). The LXD peak can be suppressed by annealing the defective MoS2 in sulfur vapor, which indicates that it is possible to passivatethe vacancies. Our results provide insights into how excitonic anddefect-mediated PL emissions in MoS2 are influenced bysulfur vacancies at room and low temperatures. |
Trushin, Maxim; Carvalho, Alexandra; Neto, Castro A H Two-dimensional non-linear hydrodynamics and nanofluidics Journal Article COMMUNICATIONS PHYSICS, 6 (1), 2023, ISSN: 2399-3650. @article{ISI:001021478100002, title = {Two-dimensional non-linear hydrodynamics and nanofluidics}, author = {Maxim Trushin and Alexandra Carvalho and Castro A H Neto}, doi = {10.1038/s42005-023-01274-1}, times_cited = {0}, issn = {2399-3650}, year = {2023}, date = {2023-07-03}, journal = {COMMUNICATIONS PHYSICS}, volume = {6}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {A water monolayer squeezed between two solid planes experiences strong out-of-plane confinement effects while expanding freely within the plane. As a consequence, the transport of such two-dimensional water combines hydrodynamic and nanofluidic features, intimately linked with each other. In this paper, we propose and explicitly solve a non-linear hydrodynamic equation describing two-dimensional water flow with viscosity parameters deduced from molecular dynamic simulations. We demonstrate that the very ability of two-dimensional water to flow in short channels is governed by the second (dilatational) viscosity coefficient, leading to flow compression and velocity saturation in the high-pressure limit. The viscosity parameter values depend strongly on whether graphene or hexoganal boron nitride layers are used to confine 2D water that offers an interesting opportunity to obtain various nanofluids out of the same water molecules just by using alternate materials to fabricate the 2D channels.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A water monolayer squeezed between two solid planes experiences strong out-of-plane confinement effects while expanding freely within the plane. As a consequence, the transport of such two-dimensional water combines hydrodynamic and nanofluidic features, intimately linked with each other. In this paper, we propose and explicitly solve a non-linear hydrodynamic equation describing two-dimensional water flow with viscosity parameters deduced from molecular dynamic simulations. We demonstrate that the very ability of two-dimensional water to flow in short channels is governed by the second (dilatational) viscosity coefficient, leading to flow compression and velocity saturation in the high-pressure limit. The viscosity parameter values depend strongly on whether graphene or hexoganal boron nitride layers are used to confine 2D water that offers an interesting opportunity to obtain various nanofluids out of the same water molecules just by using alternate materials to fabricate the 2D channels. |
Zhang, Hanwen; Poh, Eng Tuan; Lim, Sharon Xiaodai; Zhang, Yimin; Qin, Hongye; Xie, Haonan; He, Chunnian; Sow, Chorng Haur In situ strain-induced phase transition and defect engineering in CVD-synthesized atomically thin MoS2 Journal Article 2D MATERIALS, 10 (3), 2023, ISSN: 2053-1583. @article{ISI:000994586300001, title = {\textit{In situ} strain-induced phase transition and defect engineering in CVD-synthesized atomically thin MoS_{2}}, author = {Hanwen Zhang and Eng Tuan Poh and Sharon Xiaodai Lim and Yimin Zhang and Hongye Qin and Haonan Xie and Chunnian He and Chorng Haur Sow}, doi = {10.1088/2053-1583/acd0be}, times_cited = {0}, issn = {2053-1583}, year = {2023}, date = {2023-07-01}, journal = {2D MATERIALS}, volume = {10}, number = {3}, publisher = {IOP Publishing Ltd}, address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, abstract = {Alkali metal halides have recently received great attention as additives in the chemical vapor deposition (CVD) process to promote the growth of transition metal dichalcogenides (TMDs). However, the multi-faceted role of these halide salts in modulating the properties and quality of TMD monolayers remains mechanistically unclear. In this study, by introducing excessive gaseous sodium chloride (NaCl) into the CVD system, we demonstrate that preferential NaCl deposition along the monolayer edges causes large in situ strain that can invoke localized domains of high defect density and 2H to 1T phase transition. High-resolution scanning transmission electron microscopy, Raman mapping and molecular dynamics simulations revealed that higher NaCl concentrations can promote the coalescence of independent local strain domains, further increasing the 1T/2H phase ratio and defect density. Furthermore, excessive NaCl was also proven by density functional theory calculations to convert thermodynamic growth to kinetic growth, accounting for the unique cloud-shaped MoS2 crystals acquired. Compared with post-growth strain processing methods, this one-step approach for phase and defect engineering not only represents a deeper understanding of the role that NaCl plays in the CVD process, but also provides a convenient means to controllably synthesize conductive/defect-rich materials for further electrocatalysis and optoelectronic applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Alkali metal halides have recently received great attention as additives in the chemical vapor deposition (CVD) process to promote the growth of transition metal dichalcogenides (TMDs). However, the multi-faceted role of these halide salts in modulating the properties and quality of TMD monolayers remains mechanistically unclear. In this study, by introducing excessive gaseous sodium chloride (NaCl) into the CVD system, we demonstrate that preferential NaCl deposition along the monolayer edges causes large in situ strain that can invoke localized domains of high defect density and 2H to 1T phase transition. High-resolution scanning transmission electron microscopy, Raman mapping and molecular dynamics simulations revealed that higher NaCl concentrations can promote the coalescence of independent local strain domains, further increasing the 1T/2H phase ratio and defect density. Furthermore, excessive NaCl was also proven by density functional theory calculations to convert thermodynamic growth to kinetic growth, accounting for the unique cloud-shaped MoS2 crystals acquired. Compared with post-growth strain processing methods, this one-step approach for phase and defect engineering not only represents a deeper understanding of the role that NaCl plays in the CVD process, but also provides a convenient means to controllably synthesize conductive/defect-rich materials for further electrocatalysis and optoelectronic applications. |
Jiang, Yingying; Lim, Alvin M H; Yan, Hongwei; Zeng, Hua Chun; Mirsaidov, Utkur Phase Segregation in PdCu Alloy Nanoparticles During CO Oxidation Reaction at Atmospheric Pressure Journal Article ADVANCED SCIENCE, 10 (25), 2023. @article{ISI:001018137900001, title = {Phase Segregation in PdCu Alloy Nanoparticles During CO Oxidation Reaction at Atmospheric Pressure}, author = {Yingying Jiang and Alvin M H Lim and Hongwei Yan and Hua Chun Zeng and Utkur Mirsaidov}, doi = {10.1002/advs.202302663}, times_cited = {0}, year = {2023}, date = {2023-06-28}, journal = {ADVANCED SCIENCE}, volume = {10}, number = {25}, publisher = {WILEY}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {Bimetallic nanoparticle (NP) catalysts are widely used in many heterogeneous gas-based reactions because they often outperform their monometallic counterparts. During these reactions, NPs often undergo structural changes, which impact their catalytic activity. Despite the important role of the structure in the catalytic activity, many aspects of how a reactive gaseous environment affects the structure of bimetallic nanocatalysts are still lacking. Here, using gas-cell transmission electron microscopy (TEM), it is shown that during a CO oxidation reaction over PdCu alloy NPs, the selective oxidation of Cu causes the segregation of Cu and transforms the NPs into Pd-CuO NPs. The segregated NPs are very stable and have high activity for the conversion of CO into CO2. Based on the observations, the segregation of Cu from Cu-based alloys during a redox reaction is likely to be general and may have a positive impact on the catalytic activity. Hence, it is believed that similar insights based on direct observation of the reactions under relevant reactive conditions are critical both for understanding and designing high-performance catalysts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bimetallic nanoparticle (NP) catalysts are widely used in many heterogeneous gas-based reactions because they often outperform their monometallic counterparts. During these reactions, NPs often undergo structural changes, which impact their catalytic activity. Despite the important role of the structure in the catalytic activity, many aspects of how a reactive gaseous environment affects the structure of bimetallic nanocatalysts are still lacking. Here, using gas-cell transmission electron microscopy (TEM), it is shown that during a CO oxidation reaction over PdCu alloy NPs, the selective oxidation of Cu causes the segregation of Cu and transforms the NPs into Pd-CuO NPs. The segregated NPs are very stable and have high activity for the conversion of CO into CO2. Based on the observations, the segregation of Cu from Cu-based alloys during a redox reaction is likely to be general and may have a positive impact on the catalytic activity. Hence, it is believed that similar insights based on direct observation of the reactions under relevant reactive conditions are critical both for understanding and designing high-performance catalysts. |
Kazeev, Nikita; Al-Maeeni, Abdalaziz Rashid; Romanov, Ignat; Faleev, Maxim; Lukin, Ruslan; Tormasov, Alexander; Neto, Castro A H; Novoselov, Kostya S; Huang, Pengru; Ustyuzhanin, Andrey Sparse representation for machine learning the properties of defects in 2D materials Journal Article NPJ COMPUTATIONAL MATERIALS, 9 (1), 2023. @article{ISI:001016773900002, title = {Sparse representation for machine learning the properties of defects in 2D materials}, author = {Nikita Kazeev and Abdalaziz Rashid Al-Maeeni and Ignat Romanov and Maxim Faleev and Ruslan Lukin and Alexander Tormasov and Castro A H Neto and Kostya S Novoselov and Pengru Huang and Andrey Ustyuzhanin}, doi = {10.1038/s41524-023-01062-z}, times_cited = {0}, year = {2023}, date = {2023-06-26}, journal = {NPJ COMPUTATIONAL MATERIALS}, volume = {9}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Two-dimensional materials offer a promising platform for the next generation of (opto-) electronic devices and other high technology applications. One of the most exciting characteristics of 2D crystals is the ability to tune their properties via controllable introduction of defects. However, the search space for such structures is enormous, and ab-initio computations prohibitively expensive. We propose a machine learning approach for rapid estimation of the properties of 2D material given the lattice structure and defect configuration. The method suggests a way to represent configuration of 2D materials with defects that allows a neural network to train quickly and accurately. We compare our methodology with the state-of-the-art approaches and demonstrate at least 3.7 times energy prediction error drop. Also, our approach is an order of magnitude more resource-efficient than its contenders both for the training and inference part.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two-dimensional materials offer a promising platform for the next generation of (opto-) electronic devices and other high technology applications. One of the most exciting characteristics of 2D crystals is the ability to tune their properties via controllable introduction of defects. However, the search space for such structures is enormous, and ab-initio computations prohibitively expensive. We propose a machine learning approach for rapid estimation of the properties of 2D material given the lattice structure and defect configuration. The method suggests a way to represent configuration of 2D materials with defects that allows a neural network to train quickly and accurately. We compare our methodology with the state-of-the-art approaches and demonstrate at least 3.7 times energy prediction error drop. Also, our approach is an order of magnitude more resource-efficient than its contenders both for the training and inference part. |
Zhou, Jun; Wang, Zishen; Wang, Shijie; Feng, Yuan Ping; Yang, Ming; Shen, Lei Coexistence of ferromagnetism and charge density waves in monolayer LaBr2 Journal Article NANOSCALE HORIZONS, 8 (8), 2023, ISSN: 2055-6756. @article{ISI:001020692300001, title = {Coexistence of ferromagnetism and charge density waves in monolayer LaBr_{2}}, author = {Jun Zhou and Zishen Wang and Shijie Wang and Yuan Ping Feng and Ming Yang and Lei Shen}, doi = {10.1039/d3nh00150d}, times_cited = {0}, issn = {2055-6756}, year = {2023}, date = {2023-06-23}, journal = {NANOSCALE HORIZONS}, volume = {8}, number = {8}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {Charge density waves (CDWs), a common phenomenon of periodic lattice distortions, often suppress ferromagnetism in two-dimensional (2D) materials, hindering their magnetic applications. Here, we report a novel CDW that generates 2D ferromagnetism instead of suppressing it, through the formation of interstitial anionic electrons as the charge modulation mechanism. Via first-principles calculations and a low-energy effective model, we find that the highly symmetrical monolayer LaBr2 undergoes a 2 x 1 CDW transition to a magnetic semiconducting T & PRIME; phase. Concurrently, the delocalized 5d(1) electrons of La in LaBr2 redistribute and accumulate within the interstitial space in the T & PRIME; phase, forming anionic electrons, also known as 2D electride or electrene. The strongly localized nature of anionic electrons promotes a Mott insulating state and full spin-polarization, while the overlap of their extended tails yields ferromagnetic direct exchange between them. Such transition introduces a new magnetic form of CDWs, offering promising opportunities for exploring novel fundamental physics and advanced spintronics applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Charge density waves (CDWs), a common phenomenon of periodic lattice distortions, often suppress ferromagnetism in two-dimensional (2D) materials, hindering their magnetic applications. Here, we report a novel CDW that generates 2D ferromagnetism instead of suppressing it, through the formation of interstitial anionic electrons as the charge modulation mechanism. Via first-principles calculations and a low-energy effective model, we find that the highly symmetrical monolayer LaBr2 undergoes a 2 x 1 CDW transition to a magnetic semiconducting T & PRIME; phase. Concurrently, the delocalized 5d(1) electrons of La in LaBr2 redistribute and accumulate within the interstitial space in the T & PRIME; phase, forming anionic electrons, also known as 2D electride or electrene. The strongly localized nature of anionic electrons promotes a Mott insulating state and full spin-polarization, while the overlap of their extended tails yields ferromagnetic direct exchange between them. Such transition introduces a new magnetic form of CDWs, offering promising opportunities for exploring novel fundamental physics and advanced spintronics applications. |